The proposed research would employ a diversity of Drosophila species and a diversity of D. melanogaster genetic backgrounds to test evolutionary genetic findings obtained from a few D. melanogaster stocks. Firstly, it is proposed to select for postponed aging in five widely separated species within the Drosophila genus: D. melanogaster, D. simulans, D. pseudoobcura, D. repleta, and D. virilis. Each species would be collected from the wild and then established as an outbred laboratory population. Upon establishment, the species would be assayed for longevity, age- specific fecundity and physiological traits. Selection would be carried out on these populations to create 50 (5 species x 10 lines) new populations of early- and late-reproduced lines. These lines would then be compared both within and between species for patterns of genetic and physiological adaptations associated with selection for postponed aging. This in turn would address the extent to which related species have common genetic mechanisms affecting aging, and thus the extent to which genetic mechanisms that can be used to postpone aging in mice might be general to other mammalian species. Secondly, the proposed research would assemble alternative electrophoretic genotypes by hybridizing electrophoretically homozygous D. melanogaster lines, and then test these genotypes for their effects upon aging. This method involves the creation of inbred lines derived from outbred populations, where these inbred lines are fixed for different electromorphs. These inbred lines can then be crossed in multiple combinations to create hybrid genotypes that (a) possess the desired electrophoretic genotype, (b) are not inbred, and (c) come from different source populations. This allows tests for the effect of electrophoretic alleles upon aging-related characters (longevity, fecundity, stress resistance, and so on) without either inbreeding depression or confounding genetic effects of nearby alleles in accidental linkage disequilibrium, when data from multiple populations are used. The first locus that would be examined in this manner is superoxide dismutase.